Fritz needed 2 hours, 20 minutes to continue his amazing run at The Racquet Club. Fritz, who turned 18 on Oct. 28, used his big serve and strong forehand to advance to his first career ATP semifinal as the youngest American since Michael Chang won Wembley in 1989 at the age of 17

"It feels incredible," Fritz said. "You know it's a great milestone. ... I always say this is reassuring to know that I'm doing the right thing and I'm on the right track. But got to just keep doing my own thing and not let all the milestones get in your head or anything like that."

The teenager, in the event as a wild card ranked 145th in the world, will play Ricardas Berankis of Lithuania on Saturday. Berankis upset No. 3 seed Donald Young 7-6, 6-1, needing 80 minutes to advance.

Three-time defending champion Kei Nishikori beat Mikhail Kukushkin of Kazakhstan 6-2, 6-4 at night to extend his match winning streak to 15 in Memphis. Nishikori will play fourth-seeded Sam Querrey, a 6-3, 6-4 winner over Japanese qualifier Yoshihito Nishioka, in a rematch of their semifinal last year.

Becker, in his third quarterfinal at this event, had a chance to close Fritz out in the tiebreaker serving at 5-5. Becker hit a backhand long on each of the next two points, prompting the teenager to celebrate with a fist pump and dropping his racket.

"It's incredible," Fritz said. "I can't believe it. Just an amazing feeling, especially after the match I just had coming back ... he was serving for the match and to come back and win it in that way and tough it out, I'll never forget that."

Fritz came out strong despite having hotel security called on him around 1:30 a.m. for making too much noise at the ice machine for a bath. He had six of his 13 aces in the first set, but he struggled with four double-faults in dropping the second set. Fritz and Becker broke each other twice with the teenager saving the crucial break point.

This week is proving a big lesson for the teenager who upset No. 2 seed Steve Johnson on Thursday night.

"I feel like I can compete at this level," Fritz said.

Nishikori improved to 5-0 against Kukushkin. Nishikori reached his first semifinal since Tokyo last October by taking the first set in 42 minutes. In the second, he went up 5-4 when Kukushkin served up his third double-fault of the match. Nishikori had to fight back to deuce a couple times before finally putting a forehand into the corner to finish off the match.

"Everything was working well on my serve," Nishikori said. "I struggled a little bit in the second set. Obviously, he started playing better. He was more aggressive and hitting some great shots. Sometimes I have to stay focused what I have to do, and it was again tough to finish but yeah it's great to finish in two sets."

Querrey, the 2010 champion, reached his second straight semifinal in Memphis. He served up 11 aces in his first match against Nishioka, and Querrey said the ball being used at this tournament is so heavy it was tough getting shots past him. That forced Querrey to play patiently.

"The ball is fine for a different court," Querrey said. "It just isn't working well here. It's just the complete opposite of every year in the past. The ball weighs five times as heavy as it has in the past. I don't think many of the guys like it for this court."